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CHIMNEY INSPECTION DIAGNOSIS REPAIR
BACKDRAFTING HEATING EQUIPMENT
CARBON MONOXIDE - CO
CHIMNEY CAP & CROWN
CHIMNEY CLEANING PROCEDURES
CHIMNEY COMPONENT DEFINITIONS
CHIMNEY CRACK DETECTION & DIAGNOSIS
CHIMNEY DRAFT & PERFORMANCE
CHIMNEY FIRE ACTION / PREVENTION
CHIMNEY HEIGHT & CLEARANCE CODE
CHIMNEY INSPECTION, FLUE INTERIOR
CHIMNEY LEANING, SEPARATION, MOVEMENT
CHIMNEY REPAIR METHODS
CHIMNEY STAINS & LEAKS
CHIMNEY TYPES & MATERIALS
COAL STOVE OPERATION & SAFETY
DIRECT VENTS / SIDE WALL VENTS
DRAFT HOOD, GAS HEATER
DRAFT REGULATOR, DAMPER, BOOSTER
FIRE CLEARANCES INDOORS
FIREPLACES & HEARTHS
FLUE VENT CONNECTORS
MASONRY CHIMNEY GUIDE
METAL CHIMNEYS & FLUES
SAFETY RECALLS CHIMNEYS VENTS HEATERS
SOOT AT CHIMNEY TOP
STAIN DIAGNOSIS on BUILDING EXTERIORS
WOOD-OIL COMBINATION HEATERS
This article describes the antique and modern fireplace inserts used for wood, coal, or pellet fuel heating.
We discuss fireplace inserts and zero-clearance fireplaces, both antique and modern, and their hazards and inspection limitations.
The page top sketch, provided courtesy of Toronto home inspection firm Carson Dunlop Associates illustrates limitations on the visual inspection of fireplace inserts. It does not show proper fireplace insert installation details.
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Below we provide photographs of the exploration of the condition of a cast-iron "fireplace" or fireplace grate that was originally intended for burning large chunks of coal, probably soft coal. This installation was found in a home built in Poughkeepsie NY ca 1900 and restored by the author.
Watch out: Because a fireplace insert blocks direct access to the chimney flue from inside a building, the condition of an inaccessible flue is often unknown, and possibly dangerous fire or carbon monoxide hazards could be present. Expert inspection and cleaning are appropriate as at least an annual safety check. Our page top sketch of a typical fireplace insert is provided courtesy of Carson Dunlop & Associates.
Working carefully so as not to damage the ceramic tile fireplace facade and hearth, we removed and disassembled this antique coal burning fireplace insert (burning wood in our photo) to inspect the condition and construction of the chimney flue (above right). The flue was un-damaged, needed cleaning, and was also a bit small for any expanded fuel use in this installation.
Our fireplace photos above show the back and top of this coal burning insert (above left) and the grate assembly (above right).
At below left we show the solid (8" or more) masonry firebox and the opening into a basement ash pit below this fireplace. Our reproduction of an antique fireplace grate insert (below right) was a Dixon's Low-Down Grate. Low fireplace grates were intended for use over an ash pit opening. For upper floor rooms where no ash pit connection was possible, Dixon sold an Elevated Fire Grate.
The installation of low cast iron fire grates over an ash pit was made as shown in this sketch. Dixon's design intended to draw combustion air for the fire from the basement (cellar) or from outside, not from the room being heated - a design considered proper practice in modern homes and required by code in some areas. Here is another beautiful antique fireplace opening cover/grate observed in Minneapolis and contributed by Roger Hankey.
Watch out: some older homes used a shared flue among fireplaces and heating appliances on different floors - a practice that is considered unsafe and is prohibited today.
A modern fireplace insert for burning wood is shown at left. You can see why inspecting the chimney from inside is impossible without removing the appliance.
This installation is particularly interesting. If you click to enlarge the photo you can see light colored bricks at the right of the fireplace insert: the installer appears to have bricked the original fireplace opening to better fit the new insert.
Watch out: adding a fireplace insert that moves the fire doors closer to the edge of the hearth reduces fire clearance (for heat or if the doors are open, sparks and coals) between the appliance opening and nearby combustibles or flooring.
The owners have placed a "fireproof rug" in front of this unit - that semi-circular carpet observed on the floor. Is this adequate? Be sure to consult your local fire inspector when installing or converting a fireplace or fuel burning appliance.
By "fireplace insert" we refer to a wood or coal-burning stove designed to be inserted into an existing masonry fireplace opening.
The wood-stove installed in the fireplace at left may work in such a location, but it was not designed as an "insert" - and does not fit the opening of this odd fireplace. In fact not much would fit in this angled firebox.
Placing the feet of the woodstove past the hearth and onto a rug, as well as less than 3' from combustibles, are further fire hazards - this is an unsafe installation.
Details about this topic are now at FIREPLACE INSPECTION PRE-FAB - separate article. Excerpts are below
Do not confuse a fireplace insert woodstove or coalstove with a "zero-clearance" fireplace such as the unit shown here.
Zero-clearance fireplaces are typically steel constructed fireplaces to burn wood or perhaps other fuels such as LP or natural gas in modern homes, usually connected to a metal chimney.
Our photo (left) shows a zero-clearance gas fireplace. Other zero clearance fireplaces burn wood or perhaps other fuels.
The clearance to combustibles is not "zero" but one or more inches, depending on the materials, construction, and manufacturers' instructions.
Watch out: we have found a few zero-clearance fireplaces improperly installed too close to combustibles.
The installer did not understand the purpose of steel clearance-assuring projections welded to the zero-clearance fireplace, and s/he had hammered them flat to "shoe-horn" the zero clearance fireplace into a too-small wood-framed rough opening.
The result was a serious building fire hazard and a building code violation as well.
Our photo of a zero-clearance fireplace from inside the framed opening (left) shows the clearance guards intact next to our ruler.
But inspection showed chimney leaks onto this unit - evidenced by the rust and white stains that can ultimately damage the flue (at upper right) and the fireplace unit, making it unsafe.
In fact it is just about impossible to see the condition of these components and their connections unless the insert is removed or inspected from above using a chimney inspection camera system.
If a woodstove/free-standing fireplace like this were to be used it would probably require at least three feet of clearance from combustibles.
Local codes and fire regulations need to be consulted, and in most jurisdictions, a building permit and safety inspection are required for the installation of a woodstove or similar device.
Often when a fireplace insert has been installed, the original fireplace damper has been modified (cut to pass the flue vent connector) or simply removed entirely. If you are discontinuing a fireplace insert, you may need to repair or replace the fireplace damper, or perhaps install a chimney-top damper instead.
Reader comment: fireplace flue insertion distance
12/27/2014 Anonymous said:
Quite so. If you are referring to the page top sketch, that drawing does not claim to describe a proper stove insert installation; rather it illustrates areas that are not accessible for visual inspection during a home inspection. Thanks for pointing out that the sketch might confuse someone.
A fireplace insert vertical flue vent connector should indeed pass into the first vertical flue tile, subject to further installation specifications provided by the individual fireplace insert manufacturer. Any flue vent connector that connects horizontaly into a masonry chimney flue needs to be flush with the masonry flue interior. Extending an inch past that point is probably ok but extending too far into the flue horizontally is improper and is likely to block draft.
See INACCESSIBLE CONNECTIONS FIREPLACE, WOODSTOVE for details.
Continue reading at FIRE CLEARANCES, WOOD & COAL STOVE FLUES or select a topic from the More Reading links shown below.
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Frequently Asked Questions (FAQs)
(Sept 30, 2011) Glenn said:
Glenn the required fire safety clearances are specified in the installatino manual for your gas insert fireplace and will vary among manufacturers. If you give us the brand and model I'll help you find the clearance details.
(Nov 13, 2012) Richard said:
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
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